UNITED STATES MARINE CORPS · Web viewANSWER. Terrain restrictions, location of existing roads,...

UNITED STATES MARINE CORPSENGINEER EQUIPMENT INSTRUCTION COMPANY

MARINE CORPS DETACHMENTTRAINING AND EDUCATION COMMAND

FORT LEONARD WOOD, MISSOURI 65473-8963

LESSON PLAN

DESIGN A HORIZONTAL CONSTRUCTION PROJECT

E61AC03

ENGINEER ASSISTANT CHIEFS COURSE

A16EAV1

02/03/2012

APPROVED BY ___________________ DATE _______________

1

INTRODUCTION: (10 MIN)

(On CS #1)

1. GAIN ATTENTION: Horizontal construction projects are vital for the transportation of personnel and equipment, as well as the re-sup-ply of Marine units. To prevent delays, military roads and airfields must be constructed to allow for smooth operation.

(On CS #2)

2. OVERVIEW: The purpose of this period of instruction is to provide you with the fundamental knowledge to design the horizontal and verti-cal alignments for a military road.

INSTRUCTORS NOTE:Have students read the Learning Objectives in their student outline.

(On CS #3)

3. INTRODUCE LEARNING OBJECTIVES:

a. TERMINAL LEARNING OBJECTIVE(S)

1. Provided a horizontal construction mission, a scien-tific calculator, a survey set general purpose (GP), soil test set and references, design a horizontal construction project to meet con-struction mission requirements per acceptable construction stan-dards and the references. (1361-SRVY-2005 )

(On CS #4)

b. ENABLING LEARNING OBJECTIVE(S)

1. Given a horizontal construction mission, site plans, and references, identify site reconnaissance features per the MCRP 3-17A. (1361-SRVY-2005a)

2. Given written site reconnaissance data, and ref-erences, calculate the estimated storm runoff volumes per the FM 5-430-00-1. (1361-SRVY-2005b)

(On CS #5)

3. Given calculated storm runoff volumes, and refer-ences, determine culvert system requirements per the TM 5-820-4. (1361-SRVY-2005c)

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4. Given calculated storm runoff volumes, and refer-ences, determine open ditch design requirements per the FM 5-430-00-1. (1361-SRVY-2005d)

(On CS #6)

5. Given a horizontal construction mission, vehicle usage requirements, and references, determine the road classification criteria per the FM 5-430-00-1. (1361-SRVY-2005e)

6. Given a horizontal construction mission, anticipated air-craft usage requirements, and references, determine landing zone cri-teria per the FM 5-430-00-2. (1361-SRVY-2005f)

(On CS #7)

7. Given a horizontal construction mission, site re-connaissance data, a computer, software applications, andreferences, design the horizontal project alignments per the Ter-ramodel User Guide. (1361-SRVY-2005g)

8. Given a horizontal construction mission, site recon-naissance data, a computer, software applications, and references, de-sign the vertical project alignments per the Terramodel User Guide. (1361-SRVY-2005h)

(On CS #8)

4. METHOD/MEDIA: This lesson will be presented by lecture, demon-stration, and practical application. I will be aided by computer slides, VHS tape, and the dry erase board.

INSTRUCTORS NOTE:Explain lesson critique forms to students.

5. EVALUATION: A closed book performance based & multiple choice written examination, covering the material in this lesson, will be ad-ministered at the end of this period of instruction as noted on your training schedule.

6. SAFETY/CEASE TRAINING (CT) BRIEF: There are no safety/cease train-ing procedures for this period of instruction.

(On CS #9)

3

TRANSITION: Are there any questions concerning what will be covered in this lesson, how it will be covered or how you will be evaluated? Let’s start by discussing the properties of a soil.

(On CS #10)INSTRUCTORS NOTE: The time allotted for each main teaching point BODY: (15HRS 40 Min)

1. SITE RECONNAISSANCE: (30 Min) This is the initial step in plan-ning the design of a military road. The site reconnaissance is con-ducted to determine if the proposed location for the road is feasible, or if an alternate route needs to be selected. It should be conducted jointly with the Project Officer, Engineer Equipment Chief, and the Combat Engineer Chief when vertical construction is involved. Areas to concentrate on are:

(On CS #11)

a. Reconnaissance Considerations:

(1) Terrain restrictions.

(2) Location of existing roads.

(3) Location and utilization of existing bridges.

(4) Natural or man made obstacles.

(On CS #12)

(5) Vegetation and undergrowth.

(6) Engineering effort involved for construction.

(7) Existing soil conditions.

(8) Location of possible barrow pits sites.

(On CS #13)

b. Preliminary Road Location Factors:

(1) Soil Characteristics: Locate roads on terrain having the best possible subgrade soil conditions. This will decrease construc-tion efforts and make for a better road.

(2) Drainage: Locate roads in areas that easily drain, and where the construction of drainage structures are minimized.

4

(3) Topography: Avoid excessive grades and steep hills when determining the roads location. If a road must pass through steep hills, locate the road along the side of the hill instead going di-rectly over it.

(On CS #14)

(4) Earthwork: The single largest work item during the con-struction of a road is the earthwork operations. Balancing cut and fill volumes will decrease excessive hauling distances, and decrease the amount of work required to handle the material.

(5) Alignments: Keep the number of curves and grades to a min-imum. Lay all road routes with a minimum number of horizontal curves if possible. Avoid excessive vertical grades that will prevent heavier vehicles from navigating the road.

(On CS #15)

c. Final Road Location:

(1) Locate portions of new roads along existing roads whenever possible.

(2) Locate the road on soil that is stable, and easily drained. Avoid the low points of valleys, swamps, marshes, or other low lying areas because this is where water will cause surface and subsurface drainage problems.

(3) Avoid constructing roads in areas that have high water ta-bles. Locating roads through these areas will present continuing prob-lems.

(On CS #16)

(4) Locate roads along ridges and streamlines to keep the con-struction of drainage structures to a minimum. The road must be kept well above the waterline when the route follows a stream to prevent flooding.

(5) Locate roads along contour lines to avoid unnecessary earthwork operations.

(6) Select locations which avoid rock work or excessive clear-ing and grubbing if practical.

(7) Avoid sharp curves and routes which require bridging.

(On CS #17)

5

d. Recording Reconnaissance Observations: While performing the site reconnaissance, make your notes as detailed as possible using a rough checklist as a guide to collect the information for the project site.

SITE RECONNAISSANCE CHECKLIST

Project Location Existing Drawings/Maps

Project Officer Input Existing Design Specifica-tions

Combat Engineer Chief Input Public Works Coordination

Base Facilities Coordina-tion

Base Environmental Coordi-nation

Logistics Coordination External Support Require-ments

Soil Field Identification Test Hasty Runoff Calculations

Existing Terrain Existing Vegetation

Water Table Frost Line

Natural Obstacles Manmade Obstacles

Existing Roads Barrow Pit Location

Existing Bridge Location Existing Buildings

Existing Drainage Struc-tures Existing Drainage Problems

Ditching Requirements Culvert Requirements/Loca-tions

Erosion Control Require-ments

Preliminary Location Prob-lems

Final Location Justifica-tion Survey Support Coordination

Survey Alignment Data Earthwork Volumes/BOM

Foundation Drawings Structural Drawings

Building Elevations Building Details

Project Site Plan Project Plot/Grading Plan

Plan and Profile Drawing Cross Section Drawings

6

(On CS #18)

TRANSITION: During the last 30 minutes we have discussed site recon-naissance considerations. Are there any questions? I have some ques-tions for you.

OPPORTUNITY FOR QUESTIONS:

QUESTIONS TO THE CLASS:

a. What is the purpose of a site reconnaissance?

ANSWER. To determine if the selected location for the road is feasi-ble, or alternate routes need to be selected.

b. What are a couple of areas to consider when conducting a site recon?

ANSWER. Terrain restrictions, location of existing roads, location and utilization of existing bridges, natural or man made obstacles, vegetation and undergrowth, engineering effort involved for construc-tion, existing soil conditions, and the location of possible barrow pits sites.

c. What is the single largest work item involved when construct-ing a military road?

ANSWER. Earth moving operations.

TRANSITION: If there are no more questions lets talk about drainage hydrology.

(On CS #19)

2. DRAINAGE HYDROLOGY: (30 Min) The drainage (hydrology) cycle is the continuous process which carries water from the ocean to the at-mosphere, to the land, and back to sea. A number of sub-cycles can take place concurrently in the overall cycle.

(On CS #20)

a. Precipitation: Rainfall is the primary area of concern when it comes to designing and constructing drainage systems. Snow melt is of a greater concern in colder climates.

(On CS #21)

b. Interception: Rainfall coming to rest on vegetation is inter-cepted. Large quantities of water can be trapped in the leaf canopy of trees and plants.

7

(On CS #22)

c. Infiltration: A significant portion of the water that actually strikes the soil soaks into the ground. This process is called infil-tration. The rate of absorption and the quantity of water absorbed depends on the type of soil, the vegetation, the terrain slope, and the soil moistness prior to the rain. Storm-water runoff begins to accumulate only when the rate of rainfall exceeds the rate of infiltration.

(On CS #23)

d. Detention: Detention is the amount of water required to fill depressions of any size in the earth's surface. No water can leave a depression until the holding capacity of the depression has been ex-ceeded.

(On CS #24)

e. Transpiration: On a long-term basis, vegetation returns water to the atmosphere through transpiration. Because of the time in-volved, transpiration has no immediate effect on water runoff in an area.

(On CS #25)

f. Runoff: Evaporation, interception, and detention are all mois-ture losses. Runoff is the amount of precipitation minus these mois-ture losses.

(On CS #26)

g. Storms: Storms can deliver a large quantity of water to the earth in a short period of time. Storm runoff is determined by dura-tion, frequency, and intensity.

(On CS #27-28)

TRANSITION: During the last 30 minutes we have discussed drainage (hydrology). Are there any questions? I have some questions for you.



a. What is drainage hydrology?

ANSWER. The drainage (hydrology) cycle is the continuous process which carries water from the ocean to the atmosphere, to the land, and

8

back to sea. A number of sub-cycles can take place concurrently in the overall cycle.

b. What is runoff?

ANSWER. Evaporation, interception, and detention are all moisture losses. Runoff is the amount of precipitation minus these moisture losses.

c. How do you determine storm runoff?

ANSWER. Storm runoff is determined by duration, frequency, and inten-sity..

BREAK (10 min)

TRANSITION: Are there any more questions? If there are no more ques-tions lets talk about drainage.

(On CS #29)

3. DRAINAGE: (30 Min) Inadequate drainage is the most common cause of road failure. Following a few simple rules of thumb will ensure that the road to be constructed will adequately drain and prolong its service life.

a. The development of drainage systems is vital before, during, and after the construction of military roads to ensure that surface water is effectively carried away from the road surface and adjacent areas.

b. The serviceability of the road depends on the adequacy of the drainage system. A washout of a single culvert can close a road down until repaired.

(On CS #30)

c. Inadequate drainage weakens the subgrade. Estimated water runoff volumes must be determined to develop adequate drainage systems

d. To much water on military roads will cause the road to eventu-ally fail and prevent mission accomplishment.

e. Military roads use surface ditching and culvert systems to ef-fectively channel water away from the road and the adjacent areas.

9

f. To ensure drainage systems perform as designed when con-structed in very hilly or mountainous areas, erosion control measures must be incorporated into the drainage system.

(Off CS #31)

TRANSITION: What are your questions?



a. What is the most common cause for road failure?

ANSWER. Inadequate drainage

TRANSITION: During the last 30 minutes we have discussed the impor-tance of drainage. We will now discuss hasty runoff estimation proce-dures.

(On CS #32)

4. HASTY RUNOFF ESTIMATION: (60 Min) This is a method of runoff de-termination does not take into account the size, shape, and slope of the area, surface vegetation, soil conditions, or rainfall intensity. This estimation method is used when time does not permit a more exact determination, but will still enable you the determine adequate ditch-ing and culvert systems.

(On CS #33)

a. Determining the measurements of the channel is the first step and is performed during the site reconnaissance.

(1) Make a rough cross sectional sketch of the existing gully or channel you are taking measurements of.

(2) Locate a straight section along the gully or channel at, or immediately adjacent to, the construction site to take your mea-surements.

(3) Measure and record on your sketch, the inside bottom width (W1) of the existing channel to the nearest half foot.

(On CS #34)

(4) Measure and record on your sketch, the upper width (W2) at the high water mark to the nearest half foot.

(a) The high water mark is characterized by water flowing at higher than normal velocity.

10

(b) The high flow velocity tends to cause notable bank ero-sion and undercutting, and tends to retard the growth of vegetation on the banks.

(c) The high water mark is identified at the point where bank erosion or vegetation growth ceases.

(5) Measure and record on your sketch, the height (H) from the bottom of the channel, to the high water mark to the nearest half foot.

INTERIM TRANSITION: We have talked about the method of runoff determi-nation. Are there any questions? Lets take 10 and then I will demon-strate how to perform the hasty runoff estimation.________________________________________________________________________________________________________________________________________________________________________________________________

INSTRUCTOR DEMONSTRATION (30 min) Present the below example, reference the students to the power point and white board. Ensure this is explained step by step.

(On CS #35)

b. Next you must compute the approximate volume of water to be carried by an open ditch or culvert from a maximum annual runoff pro-ducing storm. Use the following trapezoidal formula to compute the cross-sectional area of the channel:

Ca = W1 + W2 x H 2

(1) Ca = Channel area (cross section) in square feet. Answer is rounded to two decimal places.

(2) W1 = Width of the channel bottom to the nearest half foot.

(3) W2 = Width of the channel at the high water mark to the nearest half foot.

(4) H = Height from the bottom of the channel to the high wa-ter mark to the nearest half foot.

(On CS #36)

EXAMPLE:

a. Compute the channel area (Ca).

11

Ca = 3.0’+ 6.0’ x 4.0’ 2

Ca = 18.00 square feet

INTERIM TRANSITION: I have just demonstrated hasty runoff estimation. Any questions before the practical application? Lets take a break be-fore the practical application.

BREAK (10 min)

INTERIM TRANSITION: Any more questions before the practical applica-tion?

(On CS #37)

INSTRUCTOR NOTE:Perform the following practical application.

PRACTICAL EXERCISE: (45min) Everyone will have 60 minutes to practice the hasty runoff estimation problems in your student outline. I will be walking around the classroom checking on your progress if you should need any help.

PRACTICE: Conduct hasty runoff estimation utilizing the procedures that were taught during class.

PROVIDE HELP: Ensure students have all training aids, such as; Prac-tical exercise Worksheets, calculators, extra sheets of paper, and references. Walkd around the classroom and aid the students in their calculations, reminding them of the reference tables provided in their handouts. Remind them that these practical exercises will be part of their examination.

1. Safety Brief: (If applicable) (Brief students on safety precautions andwhat to do if there is a mishap.)2. Supervision and Guidance: (Describe what the instructor is doing during the PAi.e. moving about the room, assisting students, answering questions.)3. Debrief: (If applicable) (Allow participants opportunity to comment on whatthey experienced and/or observed. Provide overall feedback, guidance on any misconceptions, andreview the learning points of the PA.)

12

TRANSITION: We have just covered the hasty runoff pratical exercise. Are there any questions?

(On CS #38)


1. QUESTIONS FROM THE CLASS: Do you have any questions concerning the drainage cycle or the importance of drainage? (Answer students questions.)

2. QUESTIONS TO THE CLASS:

a. When is the hasty runoff used?

ANSWER. When time does not permit a more exact determination.

b. What does the high water mark in a channel identify?

ANSWER. The high water mark is identified at the point where bank erosion or vegetation growth ceases.

c. What does the channel area (Ca) value represent?

ANSWER. The approximate volume of water to expected as a result of a maximum annual runoff producing storm.

(On CS #39)

BREAK (10 min)

TRANSITION: During the last 60 minutes we have discussed the hasty runoff estimation procedures. We will now discuss the culvert sys-tems.

(On CS #40)

5. CULVERTS: (70 Min) A culvert is an waterway enclosure used to pass water from one point to another. They are an expedient and eco-nomical way to correct or improve existing drainage problems, and to prevent drainage problems during and after construction of a military road.

(On CS #41)

a. Culvert Use:

(1) Pass water through an embankment.13

(2) Continue natural streams through an intercepting struc-ture.

(3) Provide cross drainage in a fill section of a road.

(4) Provide ditch relief.

(5) Continue side ditches at road intersections.

b. Culvert Classifications: There are two classifications of cul-vert systems that we deal with when developing drainage systems during the construction of a military road.

(On CS #42)

(1) Permanent Culverts: This culvert classification is perma-nent in nature and is constructed of such materials as:

(a) Corrugated metal pipe. (CMP)

(b) Concrete pipe. (CP)

(c) Vitrified clay pipe. (VC)

(d) Polyvinyl chloride pipe. (PVC)

(On CS #43)

(2) Expedient Culverts: Are used in expedient construction when permanent culverts are unavailable. Expedient culverts can be rapidly constructed, but require good workmanship. They provide good strength to support superimposed loads, and have the hydraulic charac-teristics that compare favorably with permanent types of culverts. Expedient culverts are constructed of such materials as:

(a) Logs and lumber

(b) Oil drums

(c) Landing mat and sandbags

c. Culvert Installation: The installation of the culvert itself is relatively simple, regardless if it is placed in an existing chan-nel or in a newly constructed channel. The following guidelines will help you supervise the installation of culvert systems within the channel.

14

(On CS #44)

(1) Fill Depth: The depth of the fill must be equal to or greater than the depth of the cover plus the diameter of the culvert. The finished road thickness is included as part of the fill depth.

(2) Cover Depth: For road culverts the minimum cover depth must be equal to half the diameter of the culvert that is used, or 12” inches, whichever is greater.

(On CS #45)

(3) Bedding: Bedding is placed in the bottom of the trench to cushion the bottom of the culvert from crushing forces. The depth of the bedding is equal to 1/10 the diameter of the culvert that is used.

(On CS #46)

(4) Culvert Slope: Installing the culvert with the proper slope (grade) will ensure that water will drain through it freely, and become self cleaning.

(a) Install culverts in existing channels so the inlet and outlet inverts match with those of the channel elevations.

(b) Slopes placed on culverts in newly constructed channels cannot be less than 0.5% in grade, or greater than 2.0% in grade.

(On CS #47)

(5) Backfill: The backfill material is hand placed and com-pacted so the placement of the culvert in the bedding is not dis-turbed. The spacing distance between the sides of the culvert to the side of the trench is equal to 1/2 the diameter of the culvert.

(On CS #48)

15

(On CS #49)

d. Maximum Culvert Diameter: Permanent culverts are selected based on their diameter. The Maximum Diameter (Dmax) method is used to calculate the maximum diameter of a culvert that can be used and still maintain the minimum amount of cover over it to prevent crushing actions. This calculation method depends on the amount of fill used to bury the culvert.

(On CS #50)

(1) Fill of 36 inches or greater: Dmax = 2/3 x Fill

(a) Dmax = Maximum culvert diameter in inches rounded to two decimal places.

(b) 2/3 = A constant that represents the minimum fill depth for the maximum diameter of culvert.

(c) Fill = Fill depth in inches rounded to two decimal places.

(On CS #51)

(2) Fill of 36 inches or less: Dmax = Fill - 12”

(a) Dmax = Maximum culvert diameter in inches rounded to two decimal places.

(b) Fill = Fill depth in inches rounded to two decimal places.

(c) 12” = A constant that represents the minimum cover depth allowed to prevent crushing actions.

(On CS #52)

INTERIM TRANSITION: During the last 90 minutes we have talked about culverts. Are there any questions? Lets take 10 and then I will demon-strate how to perform the DMAX method.

(On CS #53)

BREAK (10 min)

(On CS #54)

16

INTERIM TRANSITION: Any more questions before I demonstrate how to perform the DMAX method.


(3) EXAMPLE #1: You have a fill depth of 6 feet, with a compacted road depth of 1 foot. What is the maximum culvert diameter that can be used.

(a) Dmax = 2/3 x 7 feet

(b) 7’ x 12” = 84” (fill depth converted to inches.)

(c) 2/3 x 84”

(d) Dmax = 56 inches

(On CS #55)

(4) EXAMPLE #2: You have a fill depth of 2’- 2” deep with a compacted road depth of 7 inches. What is the maximum culvert diame-ter that can be used.

(a) Dmax = Fill - 12”

(b) 33” - 12”

(c) Dmax = 21”

(Off CS #56)

INTERIM TRANSITION: We have just finished the demonstration portion of determining maximum culvert diameter. Are there any questions? Lets take 10.

(Off CS #57)

BREAK (10 min)

INTERIM TRANSITION: Any more questions before we talk about culvert alignment.

(Off CS #58)

17

e. Culvert Alignment: During construction, the proper alignment of the culvert in the channel is a critical factor in the culvert functioning under adverse conditions.

(1) To maintain an existing drainage path, place the culvert directly in the channel bottom. If no change is made to the original path of the existing channel, the drainage will not change its direc-

tion.

(On CS #59)

(2) Sometimes the road must be constructed on a section where the channel meanders. In this case it is a good idea to cut a new path that will direct the existing channel away from the road.

(On CS #60)

(3) The road may also cut across a bend in the channel. Place the culvert at a 90 degree angle to the road, and fill and compact the bend of the channel. Place a dam at the inlet and outlet to redirect the flow of water through the culvert.

18

(On CS #61)

TRANSITION: What are your questions? If none I have some for you.


1. QUESTIONS FROM THE CLASS: Do you have any questions concerning culverts? (Answer students questions.)


a. What is the purpose of a culvert?

ANSWER. To pass water from one point to another.

b. What are the two classifications of culverts?

ANSWER. Permanent and expedient.

c. What does the Dmax calculation determine?

ANSWER. The maximum culvert diameter that can be used and still main-tain the minimum cover depth to prevent crushing actions.

TRANSITION: During the 90 minutes we have discussed the culvert sys-tems. We will now discuss the open ditch design.

(On CS #62)

6. OPEN DITCHES: (90 Min) Open ditches are located along the sides of a road to collect runoff from the road and adjacent areas and transport it to a culvert.

19

(On CS #63)

a. Types of Ditches:

(1) Triangular (V) Ditches: Triangular ditches are used to move small quantities of water. Small quantities of water mean that the calculated channel area (Ca) is less than or equal to 15 square feet.

(a) Symmetrical: Side slope ratios are equal.

(On CS #64)

(b) Non-symmetrical: Side slope ratios differ in value.

(On CS #65)

(2) Trapezoidal Ditches: Trapezoidal ditches are installed for large quantities of water runoff. Large quantities of water mean that the channel area (Ca) is greater than 15 square feet. The side slopes are symmetrical.

20

(On CS #66)

b. Side-slope Ratios: Ditches have two sloped sides with each having a respective slope ratio. This is expressed as a ratio of hor-izontal feet to vertical feet.

(1) If the side-slopes are to steep, excessive erosion will occur, and the ditch will eventually clog with sediment.

(2) The ditch slope adjacent to the road shoulder is called the front slope.

(3) The opposite slope is called the back slope.

(On CS #67)

(4) The following rule of thumb applies to side-slope ratios for shallow ditches in relatively flat terrain:

(a) Non-symmetrical “V” ditch slopes are cut at 3:1/1:1 (front slope/back slope).

(b) Symmetrical ditch slopes for “V” or trapezoidal ditches are cut at either a 2:1 slope or 3:1 slope.

(On CS #68)

INTERIM TRANSITION: During the last 90 minutes we have talked about ditches. Are there any questions? Lets take 10 and then I will demon-strate how to perform ditch calculations.

(On CS #69)

BREAK (10 min)

INTERIM TRANSITION: Are there any more questions before I demonstrate how to perform ditch calculations.

21


(On CS #70)

c. Ditch Calculations: To calculate the depth and width requirements that will ensure sufficient runoff holding capacity of the ditch, use the following formulas:

(1) Triangular Ditches:

(a) Ditch Depth: D = + 0.5

1) D = Ditch depth in feet.

2) Ca = Channel area computed previously.

3) X = Front slope ratio.

4) Y = Back slope ratio.

5) 0.5 = Safety factor constant. (1/2 foot of free-board)

(On CS #71)

(b) Ditch Width: W = D x (X + Y)

1) W = Ditch width in feet.

2) D = Ditch depth in feet.

3) X = Front slope ratio used in depth computation.

4) Y = Back slope ratio used in depth computation.

(On CS #72)

EXAMPLE #1: Given a calculated channel area (Ca) of 12 sqft., and a front slope of 3:1 and a back slope of 1:1, calculate the ditch depth

22

and width dimensions needed to adequately hold the anticipated runoff volume safely and effectively.

Depth CalculationD 122

31 0.5

D 244 + 0.5

D 6 + 0.5D2.450.5D=2.95' round up to 3’

(On CS #73)

EXAMPLE #2: Given a calculated channel area (Ca) of 5 sqft., and a front slope of 2:1 and a back slope of 2:1, calculate the ditch depth and width dimensions needed to adequately hold the anticipated runoff volume safely and effectively.

Depth CalculationD 52

22 0.5

D 104 + 0.5

D 2.5 + 0.5D1.580.5D=2.08' round to 2.0’

(Off CS #74)

INTERIM TRANSITION: Are there any questions about the demonstration before we go into the practical application.

(Off CS #75)


PRACTICAL EXERCISE: (45min) Everyone will have 15 minutes to practice the triangular ditch calculations in your student outline. I will be walking around the classroom checking on your progress if you should need any help.


PROVIDE HELP: Ensure students have all training aids, such as; Prac-tical exercise Worksheets, calculators, extra sheets of paper, and

23

Width CalculationW3 31W3 4W12

Width CalculationW2 22W2 4W8

references. Walkd around the classroom and aid the students in their calculations, reminding them of the reference tables provided in their handouts. Remind them that these practical exercises will be part of their examination.

1. Safety Brief: (If applicable) (Brief students on safety precautions and what to do if there is a mishap.)2. Supervision and Guidance: (Describe what the instructor is doing during the PA i.e. moving about the room, assisting students, answer-ing questions.)3. Debrief: (If applicable) (Allow participants opportunity to comment on what they experienced and/or observed. Provide overall feedback, guidance on any misconceptions, and review the learning points of the PA.)

(On CS #76)

INTERIM TRANSITION: We have just covered the triangular ditch calcula-tions exercise. Are there any questions before the next demonstration?


(On CS #77-78)

(2) Trapezoidal Ditches:

(a) The cross-sectional area of a trapezoidal ditch is com-puted as if it were a rectangle. The slope areas are not considered.

(b) The width of the bottom of the ditch is based on the width of the cutting edge of the equipment used to construct the ditch.

(c) The following formula is used to calculate the required depth of a trapezoidal ditch: DCa

W 0.5

1) D = Depth of ditch in feet.

2) Ca = Channel area in square feet.

3) W = Width of ditch in feet.

4) 0.5 = Safety factor constant. (1/2 foot of free-board)

24

EXAMPLE: Given a calculated channel area (Ca) of 18.8 sqft., and a front slope of 3:1 and a back slope of 3:1, a bottom width of 12 feet, calculate the ditch depth dimension needed to adequately hold the runoff volume.

(a) D = + 0.5

(b) D = 1.57 + 0.5

(c) D = 2.07’ or 2.0’ foot ditch depth.

(On CS #79)

INTERIM TRANSITION: I have just demonstrated trapezodial ditch calcu-lations. Any questions before the practical application?

(On CS #80)


PRACTICAL EXERCISE: (45min) Everyone will have 15 minutes to practice the trapezodial ditch calculations in your student outline. I will be walking around the classroom checking on your progress if you should need any help.



1. Safety Brief: (If applicable) (Brief students on safety precautions and what to do if there is a mishap.)2. Supervision and Guidance: (Describe what the instructor is doing during the PA i.e. moving about the room, assisting students, answer-ing questions.)3. Debrief: (If applicable) (Allow participants opportunity to comment on whatthey experienced and/or observed. Provide overall feedback, guidance on any misconceptions, andreview the learning points of the PA.)

25

(On CS #81)

INTERIM TRANSITION: We have just covered the trapezodial ditch calcu-lations exercise. Are there any questions? If not let’s take a 10 minute break and then we will cover erosion control.

(10 MIN BREAK)

INTERIM TRANSITION: Do you have any more questions before we talk about erosion control.

(On CS #82)

d. Erosion Control: There are several methods of erosion con-trol used in ditches. The primary concern is to slow the water veloc-ity down in extremely hilly and mountainous areas.

(1) Water that runs too slowly will cause drainage systems to clog and ultimately fail. The desirable gradient for a ditch is be-tween 0.5% and 2%. Ditches with a gradient greater than 2 percent will require erosion control.

(On CS #83)

(2) Ditches may be lined to prevent erosion.

(a) The use of concrete, asphalt, rock and mortar will not decrease the velocity of the water, but it will protect the soil.

(b) The use of grass will not only help to protect the soil but it will also reduce the velocity of the water. Grass seed is cheap, and is normally available for the construction site.

(On CS #84)

(3) Check dams are nothing more than small dams built from logs or heavy timbers that reduce the gradient of the ditch. Check dams will have a minimum spacing of 50 feet.

(a) To reduce construction effort the dams should be placed as far apart as possible, while achieving the desired gradient.

(b) Check dams should be checked periodically to allow free flow of water.

TRANSITION: What are your questions? I have some for you.

(On CS #85)

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1. QUESTIONS FROM THE CLASS: Do you have any questions concerning open ditches? (Answer students questions.)


a. What type of ditch is used to carry small quantities of wa-ter?

ANSWER. Triangular (V) ditch.

b. When are trapezoidal ditches installed?

ANSWER. When the Ca is greater than 15 square feet.

TRANSITION: During the 90 minutes we have discussed the open ditches. We will now discuss construction surveys.

(On CS #86)

7. CONSTRUCTION SURVEYS: (30 Min) The purpose of construction sur-veys is to support the construction activities for the road. Con-struction surveys are broken down into three distinct phases:

(On CS #87-88)

a. Preliminary Surveys: During this survey, control is set, a traverse of the proposed road route is established, and a topo survey is conducted to create a site plan of the project area.

b. Final Location Surveys: During this survey the centerline of the road is established, cross sections and plan and profile drawings are created, and earthwork volumes readouts are created.

c. Construction Layout Surveys: During this survey, grade stakes are set to establish the vertical alignment of subgrades and finish grades, slope stakes are set to establish the limits of earth moving operations, and culvert locations are established.

(On CS #89)

d. Alignment stakes: Alignment stakes indicate the horizontal alignment of the road and establish subgrade and finish grade eleva-tions, which guide equipment operators during earth moving operations.

(On CS #90)

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(1) Centerline Stakes: These stakes establish the location of the road centerline (CL). They are normally set at 100 foot station intervals starting at the beginning of the project (BOP), and proceed-ing to the end of the project (EOP). They are marked with station values on the front.

(On CS #91)

(On CS #92)

(2) Grade Stakes: These stakes guide grading operations during the establishment of the vertical alignment (subgrade and finish grade) for a road. They will indicate the amount of earth that must be cut or filled at each station.

(On CS #93)

(On CS #94)

(3) Slope Stakes: These stake establish the earth moving lim-its left and right of the centerline. Are placed at the left and right limits of the roadway. They identify the top of cut on the back slope of a ditch or the toe of fill on an embankment and are marked with station values and slope ratios.

(On CS #95-96)

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(On CS #97)

(4) Offset Stakes: Are placed as references to the location of the slope stakes. Offset stakes are used as a backup for surveyors to reestablish critical alignment stakes that may have been disturbed.

(On CS #98)

TRANSITION: What are your questions about construction surveys?I have some questions for you.

(Off CS #99)


1. QUESTIONS FROM THE CLASS: Do you have any questions concerning construction surveys? (Answer students questions.)


a. What are the three construction survey phases?

ANSWER. Preliminary, final location, and construction layout surveys.

b. What do centerline stakes establish?

ANSWER. The horizontal alignment of the project.

c. What do grade stakes establish?29

ANSWER. The vertical alignment of the project (subgrades and finish grades).

TRANSITION: During the last 30 minutes we have discussed construction surveys. We will now discuss construction plans.

(On CS #100)

8. CONSTRUCTION PLANS: (30 Min) Finished drawings are used in the development of all military roads. The plans not only provide the layout information for the Engineer Assistants, they are critical to the Engineer Equipment Chief as a tool to supervise construction sur-veys and earth moving operations. A complete project drawing package includes the following drawings:

(On CS #101)

a. Site Plan: A site plan must show all existing planimetric and topographic features. Terrain relief is shown by contour lines. A five foot contour interval on the map should be used to clearly show the topographic relief of the intended road route.

(On CS #102)

(On CS #103)

b. Plan and Profile Drawing: The Plan View is a "Top View" looking down on the road. The plan view is the primary drawing used for the location and layout of the road. The profile view shows the "profile" of the road. The profile is a sectional view taken along the centerline of the road and shows the plotted existing elevations and proposed gradeline elevations.

(On CS #104)

30

(On CS #105)

c. Cross Section Drawings: The cross section is a sectional view of the road, cut perpendicular to the centerline and looking in the direction of travel. There are two types of sections.

(a) Earthwork Cross Sections: These drawings show the existing ground line and the proposed road grade line. Earthwork cross sec-tions are the primary drawings used for earthwork volume estimations.

(On CS #106)

(On CS #107)

(b) Typical Cross Sections: This drawing will show the road dimensions, slope ratios, and types of material to be used to con-struct the proposed road.

(On CS #108)

31

(On CS #109)

(On CS #110)

d. Plans and Specifications: Construction plans are tools used in supervising the construction of a military road. These plans, along with specifications, must be provided to the Engineer Equipment Chief or Officer.

(1) Site Plan

(2) Plan and Profile Drawing

(3) Cross Section Drawings

(4) Earthwork Volume Estimations

(5) Layout Specifications

TRANSITION: What are your questions about construction plans?

(On CS #111)


1. QUESTIONS FROM THE CLASS: Do you have any questions concerning construction plans? (Answer students questions.)

32


a. What is the primary drawing that is used for establishing the location and layout of a project?

ANSWER. The plan and profile drawing.

b. What does a typical cross section show?

ANSWER. Show the road dimensions, slope ratios, and types of material to be used to construct the proposed road.

c. What drawings are used to generate earthwork volume esti-mates?

ANSWER. Earthwork cross sections.

TRANSITION: Lets move on to horizontal alignment.

9. HORIZONTAL ALIGNMENT: (120 Min)

(On CS #112)

a. Road Classification:

(1) The first step in the design sequence for a road is to se-lect the type of road that is required with the structural require-ments that can accommodate traffic volumes throughout the life of the road. Road types are selected based on their class. For the types of roads we are generally tasked with constructing or rehabing, the classes of roads we deal with are class C or class D.

INTERIM TRANSITION: Do you have any questions before I demonstrate?

(On CS #113)


INSTRUCTOR NOTE:Refer students to Road Design Controls in student outline to clarify.

(On CS #114)

(2) Initially, you must know the estimated vehicle usage num-bers to calculate the average daily traffic (ADT) and the design hourly volume (DHV) for the intended road.

33

(a) Average Daily Traffic (ADT): Estimated number of vehi-cles x 2 (round trip).

752 = 150 vehicles per day.

(b) Design Hourly Volume (DHV): ADT 24 (hours in one day)

150 24 = 6.25 vehicles per hour.

(c) Design Hourly Volume (DHV): ADT 0.15 (rush hour for-mula)

150 0.15 = 22.5 vehicles per hour. (rush hour)

(On CS #115-116)

(3) The ADT and DHV values are compared to the established road geometric design criteria to determine what classification of road is to be constructed. The design criteria for the class of road that has been selected must be equal to or greater than the calculated ADT or DHV for a given road class.

(4) Once the road classification has been determined, your de-sign parameters must fall within the established standards. The clas-sification of the road also establishes the standard dimensions re-quired for one and two lane military roads.(On CS #103)

ROAD DESIGN CONTROLS

Initial Design Determination:

Step #1: Compute Average Daily Traffic (ADT).

ADT = No# of estimated vehicles x 2 (round trip).

Step #2: Compute Daily Hourly Volume (DHV).

DHV = ADT / 24 (number of hours in 1 day).

*DHV = ADT x 0.15 (rush hour constant).

Step #3: Compare computed values to design controls to identify the required road type to be constructed.

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Design Controls Class C(2 Lane)

Class D(1 Lane)

1. Traffic:** ADT (45% trucks)** DHVSight distance restriction

200 to 93530 to 14040% to 80%

Under 200Under 30100%

2. Design speedAverage running speed

40 mph35 mph

30 mph25 mph

Horizontal Alignment Controls

1. Road Surfaces:Width of traffic laneWidth of road shoulderCrown slope rate per footShoulder slope per footMinimum stop sight distanceMinimum pass sight distanceMaximum degree of curvature (D)

11.5 ft4.0 ft1/2” to 3/4”3/4”275 ft1,500 ft14.5 degrees

11.5 ft4.0 ft1/2” to 3/4”3/4”200 ftN/A26.7 degrees

Vertical Alignment Controls

1. Maximum gradeMinimum gradeCritical lengthSummit curvesSag curvesAbsolute minimum curve length

10%0.30%450 ft55 ft55 ft120 ft

15%0.30%250 ft35 ft28 ft80 ft

(On CS #117)

INTERIM TRANSITION: I have just demonstrated road design control ini-tial determination. Any questions before the practical application?

(On CS #118)


PRACTICAL EXERCISE: (45min) Everyone will have 30 minutes to practice the hasty runoff estimation problems in your student outline. I will be walking around the classroom checking on your progress if you should need any help.


35


1. Safety Brief: (If applicable) (Brief students on safety precautions and what to do if there is a mishap.)2. Supervision and Guidance: (Describe what the instructor is doing during the PA i.e. moving about the room, assisting students, answer-ing questions.)3. Debrief: (If applicable) (Allow participants opportunity to comment on what they experienced and/or observed. Provide overall feedback, guidance on any misconceptions, andreview the learning points of the PA.)

PRACTICE: At this time you have 10 minutes to practice the problems which are in your practical exercise workbook. I will be walking around the classroom to assist you if you are having any problems.

(On CS #119)

INTERIM TRANSITION: We have just covered the ditch calculations exer-cise. Are there any questions?

(On CS #120)

b. Horizontal Curves: Before building a road the best possible horizontal alignment for the road must be designed. The route of the road is defined by a series of straight lines (tangents) and horizon-tal curves to smooth the transition between sets of intersecting tan-gents. The principles of designing the best horizontal alignment are as follows:

(1) The straight sections of road (tangents) should be as long as possible. Terrain conditions seldom allow for construction of a road in a continuous straight line though. Due to this, the tangents should be made as long as possible, limit the number of curves, and establish longer straight sections of road.

(2) When curves do become necessary, make the horizontal curves as smooth as possible. Longer, smoother curves increase the capacity of the roadway. A gentle curve will increase the curve length, and lengthen the tangent lengths.

(On CS #121)

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c. Before you can begin establishing the horizontal alignment of the road, you must have an understanding of the types of horizontal curves, and the elements of a curve.

INSTRUCTORS NOTE:Use dry erase board to illustrate and clarify.

(1) Types of Horizontal Curves: There are four basic types of curves. Regardless of the type, all curves are based on the elements of a simple curve.

(a) Simple curves are an arc segment of a circle that smoothes the horizontal transition (change of direction) between two tangent lines. This type of curve is the simplest to construct, and fills the need for a low-speed road design.

(b) Compound curves are two simple curves connected at a common point turning in the same direction, but have different radii for each curve segment.

(c) Spiral curves are a series of simple curves connected at different common points turning in a spiral fashion. These types of curves are normally found on interstate systems as on and off ramps.

(d) Reverse curves are two simple curves connected together at a common point turning in opposite directions. These types of curves are normally used on railroads.

(On CS #122)


(2) Elements of a Horizontal Curve: Each element of a curve is calculated to ensure that when laid out, it will geometrically fit in the road and provide a smooth transition in changes of direction.

(a) Point of Intersection (PI): The PI is the intersecting point of two tangents of the road. This is the point where horizontal curves must be built for the road. This is represented as a station value.

(b) Point of Curvature (PC): The PC is the point where the curve starts from a straight tangent line. It is the beginning point of the curve, and is represented as a station value when staked out.

(c) Point of Tangency (PT): The PT is the point at which the curve ends and connects to another straight tangent line. The PT is represented as a station value when staked out.

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(d) Tangent Distance (T): The T is the distance from the PI to PC, and from the PI to PT. This distance is used to layout the location of the PC and PT for the road curve during stake out.

(e) Radius (R): The R is the radius of the circle whose arc forms the curve. The radius defines the sharpness of the curve.

(f) Length of Curve (L): The L is the distance from the PC to the PT along the arc of the curve.

(g) Intersecting Angle (I): The I angle is the deflection angle that was measured at the PI during the initial road traverse.

(On CS #123)

d. Horizontal Curve Definitions: The degree of curvature (D) is used to determine the sharpness of the curve. The degree of curvature is established as a whole or half degree. The larger the degree of curvature is, the sharper the curve will be. When there are no limit-ing factors such as terrain, the choice of the degree of curvature must be based on the road classification criteria. The degree of cur-vature is expressed by one of two definitions:


(1) Arc Definition: The degree of curvature is the angle which subtends a 100 foot arc along the curve. This definition is used primarily in military road design.

(2) Chord Definition: The degree of curvature is the angle which subtends a 100 foot chord on the curve. This results in a slightly larger angle. This definition is used primarily in railroad design.

(On CS #124)

INSTRUCTORS NOTE:Turn on overhead display and ensure students can see display screen.

e. Alignment Design: There are several methods available for creating alignments. You may go straight to your software and create it by manually inputting coordinates, angles and distances, or simply create the alignment in Terramodel by drawing it as a polyline.

(On CS #125)


38

Q What is the definiton of and ARCA The degree of curvature is the angle which subtends a 100 foot arc along the curve. Q What is the definition of a Chord? A The degree of curvature is the angle which subtends a 100 foot chord on the curve. This results in a slightly larger angle.

(On CS #126)

10. Vertical Alignment Design: (60 Min) The particular road classi-fication establishes the maximum allowable grades that can be used to design the vertical transitions (grades) for the road to be con-structed. Whenever possible, grades should be less than the allowed maximums identified for the class of road.

a. Earthwork operations are the largest single work item done in the construction of a road. When designing the proposed gradelines, every effort must be made to balance cut and fill areas as much as possible to eliminate excessive earth moving operations.

b. The balancing of the cut and fill areas is generally done by simple observation. The key to this is by following a few simple rules of thumb:

(1) Match the design gradeline elevation with the existing ground elevation at the BOP. (Proposed grade elevation = Existing ground elevation)

(2) Match the design gradeline elevation with the existing ground elevation at the EOP. (Proposed grade elevation = Existing ground elevation)

(3) Ensure that the proposed gradelines for the tangents fall below the grade limits allowed for the road classification.

c. The first step is to begin plotting trial grade line tan-gents. These grade lines identify the proposed final vertical profile (alignment) of the road.

(On CS #127)

d. After grade lines have been established, a smooth transition must occur where vertical tangents intersect. Similar to placing curves at horizontal changes of direction, vertical changes in direc-tion require the construction of a vertical curve. Vertical curves allow for a smooth transition from one tangent grade to the next ver-tically.


39

e. Types of Vertical Curves: There are two basic types of curves. Regardless of the type of curve to be used, both types are designed the same way using different specifications that dictate their dimensions.

(1) Overt (summit) curves.

(2) Invert (sag) curves.

(On CS #128)


f. Elements of a Vertical Curve: Each element of a curve is calculated to ensure that when lain out, it will geometrically fit in the road and provide a smooth transition between design grades.

(1) Point of Vertical Intersection (PVI): The PVI is the in-tersecting point of two grade line tangents of the road. This is the point where vertical curves must be built for the road. This is rep-resented as a station value and its location was determined when the grade line tangents where plotted.

(2) Point of Vertical Curvature (PVC): The PVC is the point where the curve starts off of the first grade line tangent. It is the beginning point of the curve, and is represented as a station value when staked out.

(3) Point of Vertical Tangency (PVT): The PVT is the point at which the curve ends and connects to the second grade line tangent. The PVT is represented as a station value when staked out.

(4) Percent of Grade (G1 and G2): The G1 is the percent of grade going into the curve, and the G2 is the percent of grade coming out of the curve. These two grades intersect at the PVI.

(5) Length of Curve (L): The L is the horizontal distance from the PVC to the PVT. The distance from the PVC to the PVI is 1/2 the length, and the distance from the PVI to the PVT is also 1/2 the length.

(6) Offsets (O): The O are vertical offset distances from the grade lines to the vertical curve (ground line). The heights of the offsets are computed for each full and half station along the curve.

(7) Vertical Maximum (Vm): The Vm is the largest vertical offset distance on the curve.

40

(8) High Point (HP): If the high point of the curve cannot be determined by simple observation, then the HP station value and eleva-tion must be computed. This is a critical element because the HP of a vertical curve identifies the starting point of ditching operations.

(9) Low Point (LP): If the low point of the curve cannot be determined by simple observation, then the LP station value and eleva-tion must be computed. This is a critical element because the LP of a vertical curve identifies the location of culvert systems.

TRANSITION: What are your questions? I have some for you

(On CS #129)


1. QUESTIONS FROM THE CLASS: Do you have any questions concerning vertical alignment design? (Answer students questions.)


a. QUESTION: What are the two types of vertical curves?

ANSWER: Sag and Summit.

b. QUESTION: To balance anticipated cut and fill volumes, what must be adjusted by using simple observation (trial-and-error)?

ANSWER: Gradelines.

TRANSITION: Any more questions before we talk about stabilization methods?

(On CS #130-131)

11. Stabilization Methods: (30min) There are two primary methods of stabilizing the soil during the construction of a military road.

(On CS #132)

a. Mechanical Stabilization: This is the most widely used method of mechanical stabilization which involves blending soil mate-rials, followed by compaction. This process provides the most effi-cient type of soil stabilization.

41

(1) Blending soils is the process involving mixing one soil type with another to obtain a material that will have engineering properties better than those of the original soil.

(2) Soil blending can be used to improve the strength of an existing soil to meet minimum design requirements. This is generally performed in clays, silts, or fine sands which are low in strength.

(3) Blending can be done in place or off-site, although in place procedures are performed for most expedient operations.

(4) Soil compaction is the oldest and most important means of increasing the strength of a soil. The extent of strength that can be achieved by compaction depends on the soil type, moisture content, amount of compaction, and the method of compaction.

(On CS #133)

b. Chemical Stabilization: This process of stabilization in-volves adding granular material or chemical admixtures to the soil. Stabilization using a soil and lime or soil and Portland cement mix is more costly, but proves to be more economical in the long run.

(On CS #134)

c. Subgrades: The subgrade is the foundation of the road it-self. It must be stable and compacted well enough to support the loads it will support. If not properly developed, the road will fail.

(On CS #135)

(1) Compaction increases the strength of the subgrade soil.

(2) Compaction is relatively simple in fill areas because the layers are constantly being compacted during the construction process.

(3) Compaction in cut sections require more attention so that the subgrade will resist further compression under vehicle traffic.

(On CS #136)

d. Base Courses: The purpose of a base course is to establish the wearing surface of the road to distribute the stresses from the wheel load so that it will not exceed the strength of the underlying subgrade.

(On CS #137)

(1) Base course materials such as lime rock, crushed coral, shell, and crushed granite are materials that provide a strong surface for vehicle traffic on military roads.

42

(2) When laying the base course material, the lift thickness must be compacted to attain the required density to distribute the load. The lift thickness is based on the type of material used, the compaction equipment used, and the method of construction.

(3) As a rule of thumb, the particles used in the construc-tion and compaction of the base course should be less than or equal to 1/2 the compacted lift thickness. Example: 4" lift, maximum particle size is 2".

(On CS #138)


(On CS #139)43


1. QUESTIONS FROM THE CLASS: Do you have any questions concerning soil stabilization? (Answer students questions.)


a. What base course materials provide a strong surface for vehi-cle traffic on military roads?

ANSWER. Lime rock, crushed coral, shell, or crushed granite.

b. What are the two primary methods that are used for stabilizing a military road?

ANSWER. Mechanical and chemical stabilization.

c. What function does soil stabilization serve?

ANSWER. Strength improvement, dust control, and soil waterproofing.

(On CS #140)

SUMMARY: (10 Min)

During this lesson we covered: factors involved in planning military roads, soil properties and characteristics, stabilization and drainage, ditch design, culverts, construction support activities, horizontal alignment design, and vertical alignment design. This in-formation will aid you in the accomplishment of constructing future military roads. Take a minute break. The next lesson will start at .

REFERENCES:

FM 5-34 Engineers Field DataFM 5-335 DrainageFM 5-410 Military Soils EngineeringFM 5-412 Materials TestingFM 5-430-00-1 Volume I Planning and Design of Roads, Airfields, and Heliports in the Theater of OperationsFM 5-430-00-2 Volume II Planning and Design of Roads, Airfields, and Heliports in the Theater of OperationsAutoCad Reference Manual

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